The invention relates to a device for electrically insulating rotating components in rotary printing machines or to aggregates, such as folders, located downline from the components, the folders being usually preceded by web-processing rotary printing machines.
The published International Patent Document WO 98/47802 is concerned with a device for electrostatically charging a multilayer strand, more particularly, a paper web that is printed in a web-processing rotary printing machine. A device for electrostatically charging a multilayer strand after the individual strand layers have been brought together by oppositely polarized charging electrodes is proposed in this International patent document. The charging electrodes are arranged at both of the outerlying sides of the strand and are formed so that they contact the strand at the outer sides thereof. According to this International patent document, the charging electrodes contacting the outer sides of the web strand are preferably formed as strand-contacting rollers and are so set against the strand as to be installed directly opposite one another and mutually pressing the strand therebetween. According to this construction heretofore known from the prior art, it is also possible to form the charging electrodes as electrically conductive brushes contacting the strand.
The published European Patent Document 0 451 573 A1 relates to a deviation or deflection device in a folder, where individual printed printing copies are separated from a multilayer material web strand. A device for dividing a printing copy stream into a number of partial streams is disclosed in the folder of a rotary printing machine proposed therein. For electrostatically charging the individual printing copies, electrostatically chargeable elements are arranged in a distributed manner in circumferential direction on two adjacent deviation or deflection cylinders. A device for guiding the printing copies to the deviation or deflection cylinders is provided below the two cooperating deviation or deflection cylinders, as well as a device for removing the printing copies from the circumferential surfaces of the respective deviation or deflection cylinders for further transporting the individual printing copies to a delivery. According to the improvement heretofore known from the European Patent 0 451 573 1, the individual electrostatically chargeable elements at the circumferential or outer cylindrical surfaces of the deviation or deflection cylinders are offset 90xc2x0 from one another, so that the circumferential surfaces of the two deviation or deflection cylinders cooperating with one another, respectively, have four electrostatically chargeable elements. Polarization of the electrostatic elements is reversed during the transport of the printing copies so that the printing copies running into the nip between the deviation or deflection cylinders alternately are picked up by the one surface of one of the deviation or deflection cylinders and are pushed off by the circumferential surface of the other deviation or deflection cylinder. This results in an alternating charging of the electrostatically charged printing copies, which are separated from the material web, at conveyor belts located downline, as viewed in the travel direction of the material web, from the deviation or deflection cylinders, or gripper cylinders for accepting the printing copies at the leading edges thereof, further transport devices for the printing copies being providable downline from the gripper cylinders.
It has been found that multilayer material webs adhering to one another by static charging, lose the previously applied electrostatic charge thereof when they come in contact with the surface areas or the cutting tools of the cylinders of a cutting cylinder pair in the folder. The adhesion of the individual web strands of the multilayer material webs to one another therefore decreases. The result thereof is that relative movements between the individual web layers arise in the inlet wedge and in the outlet wedge of the corresponding cutting cylinder pair of a material web-processing folder. Relative movements of the individual material web layers, whether a relative shifting or a fluttering of the leading end of the material web or of the separated products, have an undesirable or negative effect upon the cutting precision and therefore are to be avoided. With regard to the printing copies that are separated from the leading end of the multilayer material web, the decreasing adhesive effect has the result that the respectively open pages of the products can flutter due to the resultant whipping effect, which can cause the edges to turn over.
In view of the foregoing constructions heretofore known from the prior art, it is accordingly an object of the invention to provide a device for electrically insulating rotating components in a rotary printing machine, which optimally prevents relative movements between individual material web layers of a multilayer material web, as well as consequences of the whipping effect produced when the printing copies are separated.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a device for electrostatically charging a multilayer material web, comprising electrostatic charge elements assigned to outer sides of the multilayer material web, the charge elements being disposed upline of an inlet of the multilayer material web into a cylinder group of a folder, as viewed in a travel direction of the multilayer material web, the cylinder group including cylinders formed with respective outer cylindrical surfaces, the cylinders including a cutting cylinder pair having a cutting nip into which a leading end of the multilayer material web extends, the cutting cylinder pair being provided with an electrically insulated cutting tool.
In accordance with another feature of the invention, the outer cylindrical surfaces of the cylinders of the cutting cylinder pair are provided with an electrically insulating jacket coating.
In accordance with a further feature of the invention, circumferential surface segments accomodated in respective cylinder cores of the cylinders of the cutting cylinder pair are provided with electrically insulating jacket coating sections.
In accordance with an added feature of the invention, the cutting tool is formed as an anodized cutting knife.
In accordance with an additional feature of the invention, the cutting tool is accomodated in an electrically insulated manner in a knife cylinder of the cutting cylinder pair.
In accordance with yet another feature of the invention, the charging device of the invention includes a tool holder having clamping elements for holding the cutting tool in the knife cylinder, the clamping elements being received in an insulating casing.
In accordance with yet a further feature of the invention, the charging device of the invention includes at least one electrically insulated fastener for attaching the cutting tool holder to the knife cylinder.
In accordance with yet an added feature of the invention, the fastener is surrounded by a collar-shaped insulating element formed of electrically insulating material.
In accordance with yet an additional feature of the invention, the electrically insulating element is formed of a material selected from the group consisting of a ceramic material and a PTFE or polytetrafluoroethylene component.
In accordance with still another feature of the invention, the charging device includes a charge eliminator tongue settable against the knife cylinder of the cutting cylinder pair, the charge eliminator tongue being assigned, during a stop, to the electrically insulated knife cylinder of the cutting cylinder pair.
In accordance with a concomitant aspect of the invention, there is provided a folder for processing multilayer material webs after individual layers of the multilayer material web have been brought together, including a device for electrostatically charging the multilayer material web, comprising electrostatic charge elements assigned to outer sides of the multilayer material web, the charge elements being disposed upline of an inlet of the multilayer material web into a cylinder group of a folder, as viewed in a travel direction of the multilayer material web, the cylinder group including cylinders formed with respective outer cylindrical surfaces, the cylinders including a cutting cylinder pair having a cutting nip into which a leading end of the multilayer material web extends, the cutting cylinder pair being provided with an electrically insulated cutting tool.
The advantages associated with the improvement according to the invention are primarily that the electrostatic charge, which is generated on the multilayer material web, and, therewith, the adhesive effect, is maintained when the material web leaves the inlet wedge and when the material web enters the cutting wedge, i.e., when the cutting tools and the outer cylindrical or circumferential surface areas, respectively, of the cutting cylinders of the cutting cylinder pair are contacted. Due to the electrical insulation of the circumferential surfaces by depositing an electrically insulating coating and by supporting or bearing the cutting tools in an electrically insulated manner, respectively, at the circumferential surface of the cutting cylinder, they are insulated from the discharge of the applied charge. Assurance is thereby offered that the adhesive effect at the leading free end of the multilayer material web is maintained when groove bars and cutting tools meet at the cutting cylinder pair in the cutting wedge, so that relative movements of the outer web layers do not occur with respect to the web layers situated within. This is extremely important, because the leading end of the material web is unguided when the leading end of the multilayer material web emerges from the perforating nip of the perforating cylinder pair preceding the cutting cylinder pair. The greater the adhesive effect of the mutually adhering material webs is in this state, the more securely is a passage of the inlet wedge of the cutting cylinder pair ensured. It is possible to prevent edges of the leading end of the incoming multilayer material web from turning over, because the individual material web layers of the multilayer material web adhere to one another during the passage of the cutting cylinder nip and of the preceding cutting cylinder wedge.
The consequences of the whipping effect can also be reduced due to the maintained adhesive effect of the individual layers of the multilayer printing copy, when the printing copy, respectively, is separated from the incoming material web strand, and enters into the succeeding conveyor belt pair. The whipping effect induces a serpentine motion, which continues up to the product end, in the print copies leaving the cutting nip of the cutting cylinder pair, so that the edges can turn over. The higher the dynamic effect can be maintained on the printing copy, particularly with respect to the outside layers of the multilayer material web, the lower are the results of the whipping effect, so that the quality of the printing copies separated in the cutting nip can be significantly increased, because a secure passing of the outlet wedge following the cutting nip of the cutting cylinder pair can be achieved.
In an advantageous embodiment of the invention, the circumferential surfaces of the cylinders of the cutting cylinder pair, i.e., the circumferential surfaces of the groove cylinder and of the cutting knife cylinder, can be provided with an electrically insulating coating. The electrically insulating coating preferably contains a PTFE component or can be produced from ceramic material or can contain ceramic material.
In an alternative embodiment of the cylinders of a cutting cylinder pair, the cylinders can be formed of respective cores, individual segments forming the circumferential surface area of a cylinder being accommodated at the circumferential surface thereof. The components forming the circumferential surface area of the thus structured multipartite cylinder can also be formed with an electrically insulating coating of the aforementioned materials.
In a further embodiment of the invention, the cutting tool accomodated in the cutting tool mounting support at the knife cylinder can be formed as an anodized cutting knife. In addition, the cutting tool holder itself can be held in an electrically insulating manner on the knife cylinder. For this purpose, the clamping elements accomodating the cutting tools, and the knife mounting support accomodating the clamping elements and the cutting tools can also be enclosed by an electrically insulating casing with which the aforementioned components can be introduced into the corresponding groove at the circumference of the knife cylinder. Although only one cutting tool that is accepted at the circumference of a cutting knife cylinder has been mentioned hereinabove, it is believed to be clear that the explained course of action certainly can also be applied when a number of cutting tools are accommodated at the circumference of a cutting knife cylinder.
In addition to the accommodation of the cutting tool holder for holding the cutting tools in an electrically insulating casing in a groove at the circumference of the knife cylinder, the cutting tools can yet be attached by electrically insulating fasteners to the circumference of the knife cylinder. For this purpose, the knife mounting supports accommodating the cutting tools can be fastened with screws to the cylinder or to the cylinder core, the screws being provided with electrically insulated collar elements. Assurance is thereby provided that charge flow or leakage does not occur via the cutting tool mounting support to the further components of the knife cylinder of a cutting knife pair and that the adhesive effect of the individual layers of a multilayer material web upon one another is maintained as a result of the electrostatic charge, whenever contact is made by the leading end of the multilayer material web which is electrostatically charged.
In a further improvement of the invention, a charge elimination device for the electrostatic charge, which can be activated upon stopping the operation of the cutting cylinder pair, is assigned to the corresponding cylinder of the cutting cylinder pair accommodating the electrically insulated cutting tools. The proposed charging device of the invention can be advantageously employed for multilayer material web-processing folders, which are used in newspaper rotary printing presses or in jobbing or commercial web-fed rotary printing machines. The folders can be formed as folders having a pinless operation or can be formed as combination folders.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a device for electrically insulating rotating components in rotary printing machines, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: